1. Field of Invention
The invention relates to an optical disc and its control method for the applications of storing data and controlling its number of access times.
2. Related Art
The well-known read-only optical storage media (or optical discs such as CD and DVD) allow their user to access indefinitely. Therefore, the users only need to purchase or rent only one CD or DVD and share with one another. This makes people less willing to purchase optical discs. Many manufacturers therefore hope to invent a read-only optical disc that can limit or control the total number of play times.
As shown in FIG. 1, the read-only optical discs sold on the market have two areas: one is the title key area 104 and the other is the main data area 105. The main data area is composed of scrambled original data. Both areas are recorded on the surface of the optical disc 100 by embossing. When the optical disc drive 110 accesses the optical disc 100, it first reads the data in the title key area 104 and sends the data to a first descrambler 106 of the optical disc drive 110. Once the data matches the device key 109 of the optical disc drive 110, a key is obtained. The key is then sent to a second descrambler 107 of the optical disc drive 110. At the same time, the optical disc drive 110 sends the main data read from the main data area 105 to the second descrambler 107. The main data are processed by the second descrambler 107 and restored to the original data as music or movie for the user to enjoy.